Memoize falsy values

lib/github-pages-health-check.rb

@@ -70,13 +70,19 @@ def proxied?
 
     # Returns an array of DNS answers
     def dns
-      @dns ||= Timeout::timeout(TIMEOUT) do
-        without_warnings do
-          Net::DNS::Resolver.start(absolute_domain).answer if domain
+      if @dns.nil?
+        begin
+          @dns = Timeout::timeout(TIMEOUT) do
+            without_warnings do
+              Net::DNS::Resolver.start(absolute_domain).answer if domain
+            end
+          end
+          @dns ||= false
+        rescue Exception
+          @dns = false
         end
       end
-    rescue Exception
-      nil
+      @dns || nil
     end
 
     # Are we even able to get the DNS record?
@@ -165,16 +171,17 @@ def to_hash
     alias_method :to_h, :to_hash
 
     def served_by_pages?
-      @served_by_pages ||= begin
+      if @served_by_pages.nil?
         response = Typhoeus.head(uri, TYPHOEUS_OPTIONS)
         # Workaround for webmock not playing nicely with Typhoeus redirects
         # See https://github.com/bblimke/webmock/issues/237
         if response.mock? && response.headers["Location"]
           response = Typhoeus.head(response.headers["Location"], TYPHOEUS_OPTIONS)
         end
 
-        (response.mock? || response.return_code == :ok) && response.headers["Server"] == "GitHub.com"
+        @served_by_pages = (response.mock? || response.return_code == :ok) && response.headers["Server"] == "GitHub.com"
       end
+      @served_by_pages
     end
 
     def to_json